This application claims the priority of 199 53 089.0, filed in Germany, Nov. 4, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method of generating a periodic profile on an at least approximately rotationally symmetrical blank.
Many rotationally symmetrical components have periodic structures which have to be generated in a highly precise manner. Examples of this are shaft-hub connections in which the shaft is provided in the connecting region with a profile which is to be produced in a highly precise manner and which in the assembly position engages in a hub profile which is likewise to be produced in a highly precise manner. In this case, especially high demands are imposed on the accuracy of the contour generation and on the surface quality of the joining faces by such connecting profiles in which there are large contact surfaces between shaft and hub in the assembly position, in other words the force transmission is effected mainly by friction grip (e.g. polygonal profiles or circular wedge profiles) . At present, the production of such components, as described in German Patent Document DE 44 01 199, is carried out, for example, by means of grinding processes, in which the tool movements have to be geared exactly to the profile to be produced. These production processes are very time-consuming and thus costly. There is therefore a considerable requirement for a method by means of which these periodic structures can be produced quickly and cost-effectively.
An object of the invention is therefore to propose a method by means of which periodic structures can be generated on rotationally symmetrical components in a highly precise, quick and cost-effective manner.
This object is achieved according to the invention by use of generating skiving for generating a periodic profile, except flanks of external and internal tooth systems, on an approximately rotationally symmetrical blank.
Accordingly, the kinematics of generating skiving are used to generate the periodic structures. This method has been known for a long time, but was hitherto used exclusively for the machining of involute external and internal tooth systems. The use of generating skiving for generating tooth systems is described, for example, in German Patent Documents DE 35 33 064 (corresponding to U.S. Pat. No. 4,865,497), DE 39 15 976 and DE 41 22 460 (corresponding to EP 052243).
Compared with rival processes for producing periodic structures on rotationally symmetrical components, such as, for example, milling, form milling, broaching, rotary milling, turning or grinding, the chips produced during generating skiving are especially favorable with regard to their geometrical form and chip thickness, so that especially quick machining of the desired profile is made possible. Compared with these rival processes, the productive time during the machining of the workpiece is therefore especially short in the case of generating skiving. The periodic profile is generated in a single cut, which may be followed by further equalizing and finishing cuts with the same kinematics, in order to 5 increase the quality of the workpiece. Furthermore, machine tools are now available which permit high-precision matching of the workpiece axis with the tool axis at high rotational speeds and thus permit the generation of a wide range of different periodic structures with high precision. The tool contour for a specific periodic pattern, which contour may be very complex, can be calculated exactly from the desired workpiece geometry. Generating skiving is therefore suitable in particular for the production of complex periodic structures on approximately rotationally symmetrical components, such as, for example splined shafts, circular wedge shafts, polygonal shafts, ring joint hubs and joint rings.
In order to permit high cutting speeds and thus short production times, it is favorable to use a machine tool having high-precision axes and high rates of revolution of at least 1000-2000 revolutions/minute. In the interests of a high cutting speed with high accuracy to shape of the finished workpiece, it is also expedient to set the skew angle between workpiece and tool to between 15xc2x0 and 25xc2x0, preferably approximately 20xc2x0. In addition, at the high cutting speeds occurring during generating skiving, it is advantageous to use a carbide tool which is provided with an anti-wear coating.
The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawings.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.